Proteases function as molecular switches in signalling circuits at the cell surface and in the
extracellular milieu. In light of the many proteases that are encoded by the genome, and the
even larger number of bioactive substrates, it is crucial to identify which proteases cleave a
particular substrate and which substrates individual proteases cleave. Elucidating the
substrate degradomes of proteases will help us to understand the function of proteases in
development and disease and to validate proteases as drug targets.